1. Field of the Invention
The present invention relates to the testing of semiconductor wafers.
2. Description of Related Art
The use of conductive elastic probes for measuring one or more electrical properties of a semiconductor wafer is disclosed in U.S. Pat. No. 6,492,827 to Mazur et al. It has been observed that conductive elastic probes formed from certain materials, such as platinum, iridium or tantalum, or probes having at least platinum, iridium or tantalum-coated tips work best for testing semiconductor wafers. Heretofore, it was believed that the inability to grow oxides and/or the ability to grow conductive oxides on one or more of these materials rendered them more useful for such testing. However, when using such probes to perform CV type measurements of semiconductor wafers having overlaying ultra-thin dielectric layers, an undesirable leakage current flows thorough the dielectric layers thereby adversely affecting the measurement.
What is, therefore, needed and not disclosed in the prior art is a method of measuring the response of a semiconductor wafer to a CV type stimulus applied by a contact or probe to the semiconductor wafer via an overlaying ultra-thin dielectric layer of the semiconductor wafer without causing leakage current to flow through the dielectric layer.